Coaxial Electrical Interconnect

ABSTRACT

A coaxial electrical interconnect is disclosed. The coaxial electrical interconnect can include an inner conductor including an electrically conductive spring probe. The coaxial electrical interconnect can also include an outer conductor including a plurality of electrically conductive spring probes disposed about the inner conductor. Each spring probe can have a barrel and a plunger biased out of the barrel. The plunger can have a first plunger portion external to the barrel and a second plunger portion disposed partially in the barrel. The first and second plunger portions can have different diameters. A barrel of the spring probe of the inner conductor can be located proximate a plunger of at least one of the spring probes of the outer conductor.

RELATED APPLICATIONS

This is a divisional application of U.S. application Ser. No.14/872,001, filed Sep. 30, 2015, entitled “Coaxial ElectricalInterconnect,” which is incorporated by reference in its entiretyherein.

BACKGROUND

Some electrical circuits, particularly radio frequency (RF) circuits,are impedance matched and therefore efforts are taken to provide a givencharacteristic impedance through connecting cables and electricalinterconnects that couple various components of the circuits. Often,electrical interconnects are utilized to electrically couple adjacentcircuit boards to one another. However, the spacing between such circuitboards can vary. Accordingly, spring probes, which can compress to varyin length, are typically used to electrically connect such circuitboards.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the invention will be apparent from thedetailed description which follows, taken in conjunction with theaccompanying drawings, which together illustrate, by way of example,features of the invention; and, wherein:

FIG. 1 is a coaxial electrical interconnect in accordance with anexample of the present disclosure.

FIG. 2 is a support member of the coaxial electrical interconnect ofFIG. 1.

FIG. 3 is a spring probe of the coaxial electrical interconnect of FIG.1.

FIG. 4A is a cross-sectional view of the coaxial electrical interconnectof FIG. 1 in an uncompressed configuration.

FIG. 4B is a cross-sectional view of the coaxial electrical interconnectof FIG. 1 in a compressed configuration.

FIG. 5A-5C illustrate cross-sections of different regions of the coaxialelectrical interconnect of FIG. 1, in accordance with examples of thepresent disclosure.

FIG. 6 is a coaxial electrical interconnect in accordance with anotherexample of the present disclosure.

FIG. 7 is a support structure of the coaxial electrical interconnect ofFIG. 6.

FIG. 8 is a spring probe of the coaxial electrical interconnect of FIG.6.

FIG. 9 is a coaxial electrical interconnect in accordance with yetanother example of the present disclosure.

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended.

DETAILED DESCRIPTION

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. For example, an object that is“substantially” enclosed would mean that the object is either completelyenclosed or nearly completely enclosed. The exact allowable degree ofdeviation from absolute completeness may in some cases depend on thespecific context. However, generally speaking the nearness of completionwill be so as to have the same overall result as if absolute and totalcompletion were obtained. The use of “substantially” is equallyapplicable when used in a negative connotation to refer to the completeor near complete lack of an action, characteristic, property, state,structure, item, or result.

As used herein, “adjacent” refers to the proximity of two structures orelements. Particularly, elements that are identified as being “adjacent”may be either abutting or connected. Such elements may also be near orclose to each other without necessarily contacting each other. The exactdegree of proximity may in some cases depend on the specific context.

An initial overview of technology embodiments is provided below and thenspecific technology embodiments are described in further detail later.This initial summary is intended to aid readers in understanding thetechnology more quickly but is not intended to identify key features oressential features of the technology nor is it intended to limit thescope of the claimed subject matter.

Conventional coaxial interconnects, using spring probes, have varyingimpedance mismatch dependent on the amount of compression of the springprobes. When large compression variability is required, very largeimpedance mismatch can occur. In some cases, impedance mismatch due tothe electrical interconnect may require significant on-board matching.It is therefore highly desirable to have a coaxial electricalinterconnect that can compress to vary in length while maintaining aconstant characteristic impedance independent of the amount ofcompression of the electrical interconnect.

Accordingly, a coaxial electrical interconnect is disclosed that cancompress to vary in length and maintain a characteristic impedanceregardless of the amount of compression. The coaxial electricalinterconnect can include an inner conductor including an electricallyconductive spring probe. The coaxial electrical interconnect can alsoinclude an outer conductor including a plurality of electricallyconductive spring probes disposed about the inner conductor. Each springprobe can have a barrel and a plunger biased out of the barrel. Theplunger can have a first plunger portion external to the barrel and asecond plunger portion disposed at least partially in the barrel. Thefirst and second plunger portions can have different diameters. A barrelof the spring probe of the inner conductor can be located proximate aplunger of at least one of the spring probes of the outer conductor.

In addition, an electrically conductive spring probe for a coaxialelectrical interconnect is disclosed. The electrically conductive springprobe can include a barrel and a plunger biased out of the barrel. Theplunger can have a first plunger portion external to the barrel and asecond plunger portion disposed partially in the barrel. The first andsecond plunger portions can have different diameters.

One example of a coaxial electrical interconnect 100 is illustrated inFIG. 1. The coaxial electrical interconnect 100 can be used as an RFinterconnect to accommodate variations in distance between adjacentelectrically coupled components (e.g., circuit boards) by beingcompressible in length. A characteristic impedance of the coaxialelectrical interconnect 100 can be maintained substantially constant asthe length of interconnect varies, as described further below, which ishighly desirable in impedance matched circuits.

The coaxial electrical interconnect 100 can comprise an inner conductor101 and an outer conductor 102, which can be used for signal and groundconnections, respectively. The inner conductor 101 can include at leastone electrically conductive spring probe 110 a and the outer conductor102 can include a plurality of electrically conductive spring probes 110b-f disposed about the inner conductor 101. As shown, the spring probes110 b-f of the outer conductor 102 can be disposed in a circularconfiguration about the spring probe 110 a of the inner conductor 101.It should be recognized that the inner conductor 101 and the outerconductor 102 can each include any suitable number of spring probes. Itshould also be recognized that although the spring probes 110 b-f of theouter conductor 102 are shown disposed in a circular configuration aboutthe spring probe 110 a of the inner conductor 101, the spring probes 110b-f of the outer conductor 102 can be disposed in any suitableconfiguration (e.g., shape) about the spring probe 110 a of the innerconductor 101.

The coaxial electrical interconnect 100 can also comprise a spring probesupport member 120 configured to provide mechanical support for thespring probes 110 a-f of the inner and outer conductors 101, 102. Thespring probe support member 120 is shown isolated in FIG. 2 and arepresentative spring probe 110 is shown isolated in FIG. 3.

In general, as shown in FIG. 3, the spring probe 110 can have a barrel111 and a plunger 112 disposed at least partially in an opening orcavity of the barrel and biased out of the barrel 111. The plunger 112can have a first plunger portion 113 external to the barrel 111 and asecond plunger portion 114 disposed partially in the barrel 111. Thefirst and second plunger portions 113, 114 have different diameters 130,131, respectively, which are also different from a diameter 132 of thebarrel 111. The first plunger portion 113 can have a length 133 and thebarrel 111 can have a length 134. In one aspect, discussed in moredetail below, the length 133 of the first plunger portion 113 and thelength 134 of the barrel 111 can be substantially the same, which whencombined with other similar spring probes in a coaxial electricalinterconnect can facilitate, at least in part, maintaining acharacteristic impedance of the electrical interconnect as the plungersmove relative to the barrels to accommodate variations in distancebetween adjacent electrically coupled components.

The spring probe support member 120 can include openings to receiveportions of the spring probes. For example, as shown in FIG. 2, thespring probe support member 120 can include an opening 121 a to receivethe first plunger portion 113 a of the spring probe 110 and openings 121b-f to receive the barrels 111 b-f of the spring probes 110 b-f. Thespring probe support member 120 is shown as having a cylindricalconfiguration but any suitable configuration may be utilized.

As shown in FIG. 1, the spring probe 110 a of the inner conductor 101can be inverted relative to the spring probes 110 b-f of the outerconductor 102. Thus, in one aspect, the barrel of the spring probe 110 aof the inner conductor 101 can be located proximate one or more plungersof the spring probes 110 b-f of the outer conductor 102. Similarly, theplunger of the spring probe 110 a of the inner conductor 101 can belocated proximate one or more barrels of the spring probes 110 b-f ofthe outer conductor 102. In addition, the spring probe support member120 can be engaged with the first plunger portion of the spring probe110 a of the inner conductor 101 and with the barrels of the springprobes 110 b-f of the outer conductor 102. In one aspect, the springprobes 110 a-f of the inner and outer conductors 101, 102 can besubstantially identical, although the springs probes of an electricalinterconnect as disclosed herein can include spring probes that aredifferent from one another.

The support member 120 can be constructed of any suitable material orcombination of materials, which may include a dielectric material (e.g.,a suitable polymer). In one aspect, the support member 120 can beconstructed entirely of a dielectric material. In another aspect,illustrated in FIG. 2, the support member 120 can be made of adielectric material (indicated by reference number 122) around theopening 121 a for the inner spring probe 110 a. In addition, the supportmember 120 can have a conductive material (indicated by reference number123) on the outside or periphery of the support member 120 that is atleast partially in communication with the openings 121 b-f toelectrically connect the outer spring probes 110 b-f to the sameelectrical potential.

With continued reference to FIGS. 1-3, FIGS. 4A and 4B illustrateschematic cross-sectional views of the coaxial electrical interconnect100 in an uncompressed configuration (FIG. 4A) and a compressedconfiguration (FIG. 4B), such when establishing an electrical connectionbetween two adjacent circuit boards 103, 104. The spring probe of theinner conductor 101 is referred to by reference no. 110 a and the springprobes of the outer conductor 102 are referred to collectively byreference nos. 110 b-f. The spring probes 110 a-f of the coaxialelectrical interconnect 100 can provide a certain range of motion ortravel to accommodate variations in distance or stack-up of the adjacentcircuit boards 103, 104. Thus, in one aspect, each spring probe 110 a-fcan include a spring to bias the plunger out of the barrel andaccommodate compression of the plunger into the barrel, as illustratedby a spring 115 of the spring probe 110 a. The spring-loaded probes canprovide a reliable electrical contact between electrical components thatmay be located at a variable or unknown distance from one another. Theconfiguration of the spring probes 110 a-f can provide any suitablerange of motion or travel to accommodate a given maximum variation indistance between electrical components. The ends of the spring probes110 a-f in contact with the circuit boards 103, 104 can be electricallycoupled to the circuit boards in any suitable manner, such as by springforce or by soldering if a fixed connection is desired. In one aspect,no shrouds are needed for electrical purposes, but shrouds can be usedfor mechanical reasons, such as to provide protection and/or support.

In one aspect, the length 130 a of the first plunger portion 113 a ofthe spring probe 110 a of the inner conductor 101 and the lengths 134b-f of the barrels 111 b-f of the spring probes 110 b-f of the outerconductor 102 can be equal or substantially equal in length. Similarly,the length 133 b-f of the first plunger portions 113 b-f of the springprobes 110 b-f of the outer conductor 102 and the length 134 a thebarrel 111 a of the spring probe 110 a of the inner conductor 101 can beequal or substantially equal in length. As explained below, providingthe first plunger portions 113 a-f and the barrels 111 a-f withsubstantially equal lengths can facilitate maintaining a characteristicimpedance of the electrical interconnect 100 as the plungers 112 a-fmove relative to the barrels 111 a-f.

The coaxial electrical interconnect 100 can also be divided into severalregions, as a first region 141, a second region 142, and a third region143, which can each have a nominal characteristic impedance. Suchnominal characteristic impedances can be the same for all regions orthey may vary from one another, as desired. The first region 141 of theelectrical interconnect 100 can include the first plunger portion 113 aof the spring probe 110 a of the inner conductor 101 and the barrels 111b-f of the spring probes 110 b-f of the outer conductor 102. The secondregion 142 of the electrical interconnect 100 can include the secondplunger portions 114 a-f of the spring probes 110 a-f of the inner andouter conductors 101, 102 that are exposed or external to the barrels111 a-f. The third region 143 of the electrical interconnect 100 caninclude the barrel 111 a of the spring probe 110 a of the innerconductor 101 and the first plunger portions 113 b-f of the springprobes 110 b-f of the outer conductor 102. Note that the length of thesecond region 142 changes as the coaxial electrical interconnect 100 iscompressed (e.g., from length 135 in FIG. 4A to a shorter length 135′ inFIG. 4B). Because the second plunger portions 114 a-f are partiallydisposed in the barrels 111 a-f and move in and out of the barrelsdepending on the amount of compression of the coaxial electricalinterconnect 100, the second region 142 is the only one of the threeregions in FIGS. 4A and 4B that undergoes a change in length as theinterconnect 100 is compressed. Thus, the lengths of the first and thirdregions 141, 143 are unaffected by compression of the interconnect 100,while the second region 142 adjusts in length for the amount ofcompression.

Viewed in cross-section in FIGS. 5A-5C, the first region 141, the secondregion 142, and the third region 143, respectively, can each beconfigured to provide a given characteristic impedance. Generally,characteristic impedance is determined by the geometry and materials ofthe electrical interconnect. In this case, characteristic impedance ofeach region 141-143 can be calculated using the diameters of the innerconductor 101 and the outer conductor 102, as well as accounting for asupport structure (e.g., the spring probe support member 120) of theelectrical interconnect where applicable. In one aspect, the material ofthe spring probe support member 120 can be used to tune thecharacteristic impedance of the region in which it resides (i.e., thefirst region 141 in this example). A support structure can interfacewith components of the first, second, and/or third regions as desired.The spring probe 110 a of the inner conductor 101 is shown located atthe center of a circular arrangement of the spring probes 110 b-f. Thecenters or longitudinal axes of the spring probes 110 b-f lie on acircle 150, which remains the same diameter and at the same locationrelative to the spring probe 110 a for each region 141-143 because thespring probes 110 b-f are parallel to one another, although otherconfigurations are possible. A circle 151, 151′, 151″ of FIGS. 5A-5C,respectively, bounds the spring probes 110 b-f and defines a diameter ofthe outer conductor 102 for each region 141-143.

Due to the relationship of the diameter 130 for the first plungerportions 113 a-f, the diameter 131 for the second plunger portions 114a-f and, the diameter 132 for the barrels 111 a-f, the diameters of thecircles 151, 151′, 151″ (i.e., the diameters of the outer conductor 102)decrease from the first region 141 to the third region 143 while thediameters of the inner conductor 101 increase from the first region 141to the third region 143. This inverse relationship in effectivediameters of the inner and outer conductors 101, 102 from the firstregion 141 to the third region 143 can be utilized to configure thecharacteristic impedances for each region such that the characteristicimpedances are equal across the regions. Thus, for the first region 141,where there is crowding in the outer conductor 102 due to the relativelylarge diameter of the barrels 111 b-f, the diameter of the innerconductor 101 is at its smallest (e.g., the diameter of the firstplunger portion 110 a). This configuration of the first region 141, whenaccounting for the presence of the support member 120 material, whichmay be a dielectric material (e.g., a suitable polymer), can provide acharacteristic impedance that is equal to the characteristic impedanceof the second region 142 where the crowding in the outer conductor isreduced as the diameter of the inner conductor increases, and equal tothe characteristic impedance of the third region 143 where the crowdingin the outer conductor is reduced even further as the diameter 132 ofthe inner conductor 101 increases even more. Thus, the coaxialelectrical interconnect inner and outer diameters 101, 102 can changewith each of the regions 141-143 while maintaining a consistent orconstant characteristic impedance across the regions. The spring probes110 a-f of the inner and outer conductors 101, 102 can be sized andpositioned relative to one another to provide given characteristicimpedances for the first, second, and third regions 141-143 and/or thecoaxial electrical interconnect 100 as a whole. It should be recognizedthat identical spring probes can be utilized throughout the interconnect100 or interconnect 100 can incorporate different spring probes, whichmay have different diameters for the barrels, and plunger portions.

As mentioned with regard to FIGS. 4A and 4B, because the lengths of thefirst and third regions 141, 143 are unaffected by compression of theinterconnect 100, these regions will maintain the same characteristicimpedance during compression of the interconnect 100. Furthermore,because the second region 142 merely changes in length (e.g., fromlength 135 to length 135′) while the cross-section illustrated in FIG.5B remains the same, the characteristic impedance of the second regionwill also be maintained during compression of the interconnect 100.Thus, the second region 142 can adjust in length for the amount ofcompression of the interconnect 100 without altering the characteristicimpedance of the second region 142. In other words, the characteristicimpedance of the interconnect 100 can be maintained substantiallyconstant or stable throughout the range of travel of the spring probes110 a-f. As a result, compression of the interconnect 100 can have aminimal effect on impedance mismatch over a wide frequency band. Theinterconnect 100 can therefore provide for a high variability ofcompression without degrading voltage standing wave ratio (VSWR)independent of the compression of the interconnect 100.

The first plunger portion 110 a and/or any of the barrels 111 b-f of thespring probes 110 a-f can be movable or fixed relative to the supportmember 120. For example, the first plunger portion 110 a and/or any ofthe barrels 111 b-f can be threadedly coupled, adhesively coupled, orconfigured to have an interference fit with the support member 120 tosecure the first plunger portion 110 a and/or any of the barrels 111 b-fto the support member 120.

The tips of the spring probes and the protrusion from the support membernear the circuit board 103 are examples of instances where thecharacteristic impedance is not consistent with the nominalcharacteristic impedance for a given region, as determined based on thecross-sections of FIGS. 5A-5C. Similarly, although the lengths 133 a,134 b-f of the first plunger portion 113 a and the barrels 111 b-f inthe first region 141 are substantially equal, and the lengths 134 a, 133b-f of the barrel 111 a and the first plunger portions 113 b-f in thefirst region 141 are substantially equal, slight variations in theselengths due to manufacturing tolerances may result in local instanceswhere the characteristic impedance is not consistent with the nominalcharacteristic impedance for a given region. These variances from thenominal characteristic impedance can be adjusted or controlled based onthe application. For example, a high frequency application may be lesstolerant than a lower frequency application and therefore maynecessitate tighter control on such local variations from the nominalcharacteristic impedance than for a lower frequency application. Thus,terms such as “substantially,” “maintain,” and “constant” when used inthe context of component dimensions or characteristic impedance will beunderstood by one skilled in the art in light of the particularapplication of the coaxial electrical interconnect.

FIG. 6 illustrates a schematic cross-sectional view of a coaxialelectrical interconnect 200 in accordance with another example of thepresent disclosure. The coaxial electrical interconnect 200 is similarto the coaxial electrical interconnect 100 discussed above in manyrespects. In this example, several features are illustrated that canfacilitate capture or retention of spring probes and/or spring probecomponents as well as provide mechanical support for the spring probes.In this case, an inner conductor 201 can have a spring probe 211 a andan outer conductor 202 can include six spring probes referred tocollectively by reference nos. 210 b-g. First plunger portion 213 a ofthe spring probe 210 a can be received in an opening 221 a of a springprobe support member 220, and barrels 211 b-g of the spring probes 210b-g can be received in openings 221 b-g of the spring probe supportmember 220. The first plunger portion 213 a and the barrels 211 b-g andcan be configured to move or slide relative to the spring probe supportmember 220 in the openings 221 a-g, respectively. An additional springprobe support member 222 can be coupled to the spring probe supportmember 220 to capture or retain the spring probes 210 a-g as well as toprovide mechanical support for the spring probes. The spring probesupport members 220, 222 are shown isolated in FIG. 7 and arepresentative spring probe 210 is shown isolated in FIG. 8.

The spring probe 210 can include a detent 216 in a barrel 211 tointerface with a capture feature 217 of a second plunger portion 214 ofa plunger 212 to maintain the plunger 212 at least partially within thebarrel 211. The second plunger portion 214 and the detent 216 can beconfigured to provide a suitable range of motion for the plunger 212relative to the barrel 211. The spring probe 210 can also include acapture feature 218, such as a flange on the barrel 211, to capture orretain the spring probe with the spring probe support members 220, 222.The spring probe support member 220 can include one or more recesses223, such as a counter bore. The recess 223 can be configured toaccommodate the capture features 218 b-g on the barrels 211 b-g of theouter conductor 202 spring probes 210 b-g, as shown in FIG. 6. Thespring probe support member 222 can have an inner diameter 224configured to provide a mechanical interference with the capturefeatures 218 b-g of the barrels 211 b-g in the recess 223, which canlimit a range of motion for the barrels relative to the support member220 and capture or retain the spring probes 210 b-g of the outerconductor 202 with the spring probe support members 220, 222. The springprobe support member 222 can also have an end 225 with alignmentopenings 226 a-g configured to receive the first plunger portions 213b-g of the spring probes 210 b-g of the outer conductor 202 and thebarrel 211 a of the spring probe 210 a of the inner conductor 201. Theopenings 226 a-g can be sized to allow movement of the first plungerportions 213 b-g and the barrel 211 a relative to the spring probesupport member 222 during compression of the interconnect 200, whileproviding adequate mechanical support for lateral deflection of thespring probes 210 a-g. The opening 226 a for the barrel 211 a can alsobe configured to provide a mechanical interference with the capturefeature 218 a of the barrel 211 a to capture or retain the spring probe210 a of the inner conductor 201 with the spring probe support members220, 222. In one aspect, an outer portion or surface of the spring probesupport member 220 and/or the spring probe support member 222 cancomprise an overloading type of dielectric material (e.g., metalizedplastic) to create a ground shield around the spring probes 210 a-g.

The presence of the spring probe capture features 218 a-g may introducea slight impedance mismatch. For example, the flanges on the barrels 211a-g as well as the spring probe support member 222 can introducematerial that can cause local variations in the nominal impedance of agiven region. As mentioned above, these local variations in impedancecan be reduced or minimized depending on the application to acceptablelevels. For example, the interconnect 200 can be fine-tuned for higherfrequency applications by including local diameter expansions 219 aand/or contractions 219 b in adjacent components to offset the presenceor absence of material in a neighboring component (e.g., detent 216 aand capture feature 218 a). In one aspect, a material, such as adielectric material, can be included strategically to address localimpedance variations. As shown in FIGS. 6 and 7, the spring probesupport member 222 can be hollowed out with a minimal amount of materialat the end 225 to provide mechanical support for the spring probes 210a-g. In one aspect, the spring probe support member 222 can beconfigured with holes, suitable material type, etc, to approximate theresistance of air so that impedance is maintained within acceptablelevels locally.

FIG. 9 illustrates a schematic cross-sectional view of a coaxialelectrical interconnect 300 in accordance with yet another example ofthe present disclosure. The coaxial electrical interconnect 300 includesmany similarities to the coaxial electrical interconnects 100 and 200discussed above. In this example, the electrical interconnect 300 isconfigured with spring probes 310 a-g that are double-ended, whereas thespring probes of the electrical interconnects 100 and 200 aresingle-ended. Thus, the spring probes 310 a-g can compress independentlyon opposite ends of the interconnect 300. In this case, the spring probe310 a of an inner conductor 301 comprises two barrels 311 a, 311 a′oriented on opposite ends of a plunger 312 a, and the spring probes 310b-g of an outer conductor 302 comprise two plungers 312 b-g, 312 b′-g′oriented on opposite ends of a barrel 311 b-g. The spring probes 310 a-gutilized in this example therefore are not all alike or identical. Theresult of such a configuration is five different regions 341-345, eachof which can be configured to have a given nominal characteristicimpedance, as described herein. It should be recognized that anysuitable number of different regions can be utilized.

In accordance with one embodiment of the present invention, a method forfacilitating a matched impedance electrical connection is disclosed. Themethod can comprise providing a coaxial electrical interconnect, havingan inner conductor including an electrically conductive spring probe,and an outer conductor including a plurality of electrically conductivespring probes disposed about the inner conductor, each spring probehaving a barrel and a plunger biased out of the barrel, the plungerhaving a first plunger portion external to the barrel and a secondplunger portion disposed partially in the barrel, the first and secondplunger portions having different diameters, wherein a barrel of thespring probe of the inner conductor is located proximate a plunger of atleast one of the spring probes of the outer conductor. Additionally, themethod can comprise facilitating a constant characteristic impedance ofthe electrical interconnect as the plungers move relative to thebarrels. In one aspect of the method, facilitating a constantcharacteristic impedance can comprise sizing the first plunger portionof the spring probe of the inner conductor and the barrels of the springprobes of the outer conductor with substantially equal lengths. It isnoted that no specific order is required in this method, thoughgenerally in one embodiment, these method steps can be carried outsequentially.

It is to be understood that the embodiments of the invention disclosedare not limited to the particular structures, process steps, ormaterials disclosed herein, but are extended to equivalents thereof aswould be recognized by those ordinarily skilled in the relevant arts. Itshould also be understood that terminology employed herein is used forthe purpose of describing particular embodiments only and is notintended to be limiting.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, appearancesof the phrases “in one embodiment” or “in an embodiment” in variousplaces throughout this specification are not necessarily all referringto the same embodiment.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary. In addition, various embodiments and example of the presentinvention may be referred to herein along with alternatives for thevarious components thereof. It is understood that such embodiments,examples, and alternatives are not to be construed as de factoequivalents of one another, but are to be considered as separate andautonomous representations of the present invention.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thedescription, numerous specific details are provided, such as examples oflengths, widths, shapes, etc., to provide a thorough understanding ofembodiments of the invention. One skilled in the relevant art willrecognize, however, that the invention can be practiced without one ormore of the specific details, or with other methods, components,materials, etc. In other instances, well-known structures, materials, oroperations are not shown or described in detail to avoid obscuringaspects of the invention.

While the foregoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

What is claimed is:
 1. A coaxial electrical interconnect, comprising: aninner conductor including an electrically conductive spring probe; andan outer conductor including a plurality of electrically conductivespring probes disposed about the inner conductor, each spring probehaving a barrel and a plunger biased out of the barrel, the plungerhaving a first plunger portion external to the barrel and a secondplunger portion disposed partially in the barrel, the first and secondplunger portions having different diameters, wherein a barrel of thespring probe of the inner conductor is located proximate a plunger of atleast one of the spring probes of the outer conductor.
 2. The coaxialelectrical interconnect of claim 1, wherein the spring probes of theinner and outer conductors are substantially identical.
 3. The coaxialelectrical interconnect of claim 1, wherein the spring probes of theouter conductor are disposed in a circular configuration about thespring probe of the inner conductor.
 4. The coaxial electricalinterconnect of claim 1, further comprising a spring probe supportmember configured to provide mechanical support for the spring probes ofthe inner and outer conductors.
 5. The coaxial electrical interconnectof claim 4, wherein the spring probe support member is constructed of adielectric material.
 6. The coaxial electrical interconnect of claim 4,wherein the spring probe support member is engaged with the firstplunger portion of the spring probe of the inner conductor and with thebarrels of the spring probes of the outer conductor.
 7. The coaxialelectrical interconnect of claim 6, further comprising a second springprobe support member coupled to the first spring probe support member,the second spring probe support member configured to provide mechanicalsupport for the barrel of the spring probe of the inner conductor andthe first plunger portions of the spring probes of the outer conductor.8. The coaxial electrical interconnect of claim 7, wherein the barrelsof the spring probes comprise capture features, and wherein the firstand second spring probe support members are configured to providemechanical interference with the capture features to maintain the springprobes with the first and second support members.
 9. The coaxialelectrical interconnect of claim 1, wherein each spring probe comprisesa spring to bias the plunger out of the barrel.
 10. The coaxialelectrical interconnect of claim 1, wherein the spring probe of theinner conductor comprises two barrels oriented on opposite ends of theplunger.
 11. The coaxial electrical interconnect of claim 1, wherein thespring probes of the outer conductor comprise two plungers oriented onopposite ends of the barrel.
 12. The coaxial electrical interconnect ofclaim 1, wherein the first plunger portion of the spring probe of theinner conductor and the barrels of the spring probes of the outerconductor are substantially equal in length to facilitate maintaining acharacteristic impedance of the electrical interconnect as the plungersmove relative to the barrels.
 13. The coaxial electrical interconnect ofclaim 1, wherein the spring probe of the inner conductor and theplurality of spring probes of the outer conductor are sized andpositioned relative to one another to provide a given characteristicimpedance.
 14. The coaxial electrical interconnect of claim 1, wherein afirst region of the electrical interconnect comprises the first plungerportion of the spring probe of the inner conductor and the barrels ofthe spring probes of the outer conductor, a second region of theelectrical interconnect comprises the second plunger portions of thespring probes of the inner and outer conductors, and a third region ofthe electrical interconnect comprises the barrel of the spring probe ofthe inner conductor and the first plunger portions of the spring probesof the outer conductor, and wherein the spring probes of the inner andouter conductors are sized and positioned relative to one another toprovide given characteristic impedances for the first, second, and thirdregions.
 15. The coaxial electrical interconnect of claim 14, whereinthe given characteristic impedances of the first, second, and thirdregions are the same.
 16. The coaxial electrical interconnect of claim14, wherein the first region further comprises a dielectric supportmember configured to provide mechanical support for the spring probes ofthe inner and outer conductors.
 17. The coaxial electrical interconnectof claim 1, wherein the spring probe of the inner conductor is invertedrelative to the spring probes of the outer conductor.
 18. Anelectrically conductive spring probe for a coaxial electricalinterconnect, comprising: a barrel; and a plunger biased out of thebarrel, the plunger having a first plunger portion external to thebarrel and a second plunger portion disposed partially in the barrel,the first and second plunger portions having different diameters.